Born in West Medford, Massachusetts as one of ten children, Kelley ran track and cross-country at Arlington High School in Massachusetts. He did not finish his first Boston Marathon in 1928, but eventually competed in a record 61 Boston Marathons. A legend of the marathon, Kelley won the 1935 and 1945 runnings of the Boston Marathon. He finished in second place at Boston a record seven times. Between 1934 to 1950, he finished in the top five 15 times at Boston, consistently running in the 2:30s. He ran his last full marathon at Boston in 1992 at the age of 84, his 61st start and 58th finish there.